This icon was a part of a 12-icon set of menological (annual) Calendar icons and represents the month of April.
Known as synaxaria (monthly), twelve monthly panels of the Calendar icons are exhibited in the church one at a time on a special lectern called the analogion and depict images of saints arranged chronologically according to their feast days in alteration with the movable liturgical feasts as they distributed in the Orthodox calendar for one specific month.
Although, most saints are represented standing, Saint George, whose feast falls on the 23rd of April, is depicted during his Miracle of Slaying the Dragon. The saints are arranged in four rows, each row signifying a calendar week of a month with portraits of saints venerated during this week. The layout and color scheme of this “calendar of sainthood” play a role in their legibility and practical use.